OK, this page is still a work in progress but I had people asking so I decided to just post it as is and pad it out as I got the rest of the stuff finished.
To some extent this plane is what I wanted and to other extents it's not quite what I wanted. This was due to a couple compromises that I made along the way for the sake of the project. Scratchbuilt Parkjets are a very subjective thing and not everyone wants the same set of values in the finished plane.
My idea was to produce a "middle of the road" plane capable of performing "nicely" at a number things. I wanted well-rounded aerobatic performance as well as a bit of zip in a straight line for the "speed freeks" while at the same time sticking to a strict budget set by outside forces rather than my own ideas.
The general idea was to find a way to put myself back into the position of someone relatively new to the hobby. By picking a strict budget and using the RCPowers.com Master Parts List (or commonly suggested equivalents), this severly limited the liberties I could take because of the knowledge, building skills and flying skills I have accumulated in the last 18 months.
In the end, though it's not exactly what I wanted out of the plane to start with, it's grown on me and I'm going to keep it as it is. It's turned out to be a fun "middle of the road" plane that a lot of people can get a fair bit of enjoyment out of.
The Plan!
The plan was to follow a relatively simple build from the very first steps right through to the finished plane so beginners could get a peek into what they were in for. This means, by default, stopping short of anything I consider more suitable to "intermediate" builders/flyers.
Then, I would pause at certain steps and make videos about the plane, my selections, methods and why I chose to do things a certain way. I'd also make comparisons before and after each step, or to other planes made from the same plans, to help people decide on which steps they would like to take and which they would like to bypass.
I also attached a dollar value. The entire plane, minus foam and freight, must be able to be built for no more than $75.00. I chose this mainly because a decent Plug and Fly plane is going to cost you $65-$75 from hobbyking. Keeping foam out of this allowed for the extra that people were willing to pay to get the satisfaction of building themselves as well as the widely varying prices of different foams.
While there's many foams available, I used Depron which cost me about $10.75 a sheet here in Australia. This is expensive for most places in the world! Not only is Depron cheaper in many places, other even cheaper foams are readily available.
I was willing to break $75.00 in order to shop local, but I still had to be able to buy all of the parts for that so the results could be duplicated by those on a budget. Otherwise it starts getting cheaper to simply look at ARF planes on Hobbyking and the like.
The reason for that price cap? ARF and RTF packages are great. I have a couple myself and enjoy them immensely however those tend to be about flying. Scratchbuilt parkjets are as much about the satisfaction of building as the fun of flying so I wanted to keep this grounded in "hobby" territory on a comparable budget to ARF/RTF "flying".
Step one: Choose plans.
I wanted a slick looking plane. I wanted it to be something that not only flew well but was also capable of turning heads. So something with a 3D fuselage was the go because profile planes generally tend to have all of the electronics out on display. It couldn't be too complicated that someone on their second or third build couldn't do without a bunch of frustration.
To keep costs down it also had to fly well on an elevon only setup and be reasonably quick in the speed department. I also wanted the size to be somewhat impressive for the price.
While I was looking for a plane, serendipity struck and I ended up with the plans for the Mig 29 v2 from RCPowers.com. It's the smallest of their "V2" planes which are fairly large for scratchbuilt parkjets. It already had a reputation as a quick plane, for maneuverability, as well as a certain "lack of fuss" on what you did to it.
The choice was made.
<Misisng video: Topic - the advantages of buying plans vs using free ones>
Step 2: Choose power system.
For various reasons I wanted to keep this as close to the RCPowers.com Master Parts List recommendations as was sensible.
I also wanted to make sure that not only would the setup be suitable for the larger "RCPowers v2" planes but would also be light enough for the average flyer to build the smaller "one sheet of foam" parkjets.
I'd lost $13 I had counted on up front by buying plans but I didn't think it was going to make a huge difference.
However I knew that the RCTimer 2826-6 2200kv + RCTimer 30A ESC was a good combo offering power on a reasonable budget. The motor and ESC costs you $21.98 but you also have to get the plugs to go with them. I knew I wanted the plane to go vertical and do it well. The RCT 2826-6 on the right 6x4 prop can give you about 870g of thrust at 30 amps. It's nice but not astronomical. Being that the battery is a source of a lot of weight there was another choice to be made. I had to cover my amp draw and keep the weight down. Again I spent more money than I really had to.
There are lighter motors on offer that will fly this plane well in many ways and still go vertical on the right setup and build. RCPowers recommends a smaller motor as stock too. However something I've noticed lately is that a lot of people are outgrowing these smaller motors quite quickly. Sometimes it's because lack of skill or choice of components just makes the plane a little to heavy for them, sometimes it's because they want to lean more towards speed. I wanted the setup I ended up using being suitable to keep someone going for at least a couple months to see them through to the "intermediate" stage where the more powerful and complicated setups start to make more sense.
Getting to battery selection, I needed at least a 1600mAh 3s 20C battery to give me the headroom I wanted over the draw from the motor. Looking at Hobbyking I compared the Turnigy and Zippy batteries. The Zippy turned out to be about a dollar cheaper but, more importantly, 15 grams lighter (half an ounce give or take). This made it more suitable for the smaller "one sheet of foam" parkjets out there where wing loading is concerned.
I didn't add this to the price! ARF planes do not come with batteries but they do come with a battery recommendation. This means I could have gone more expensive on the batteries and selected a good brand (or Turnigy Nanotech) but budget is a theme I wanted to stick to.
For servos the cheapest in the RCPowers Master Parts list is $7 each which I wanted to avoid. However, the RCTimer TS9025MG servos are virtually identical to the TowerPro MG90's in the Master Parts list but $1 each cheaper.
Note: I ended up using TS9018MG servos because I had some here! They are a bit weaker and a bit lighter but in the end it makes not much difference. I do recommend the TS9025MG's instead tho.
After that it's;
5 Minute Epoxy - Hobbyking
2mm bullet connectors - Hobbyking
Plug to fit battery (XT90 in this case).
Carbon Rod/tube (1m x 750mm) x 2
Control rods (10 pack) - Hobbyking
Nylon Clevis - Hobbyking (10 pack)
Control horns x 2 (self cut)
Motor mount (self cut)
PC style 6x4 prop (two pack) - Hobbyking
self-tapping screws (x2) - Local Hardware Store
Plan printing - $6.60 (local printshop)
Velcro - local $2 shop
Roll of Hinge Tape - local $2 shop.
Up to this point I am sitting on $67.43. I WILL end up breaking my budget by the time I'm done (by about $4.00).
Note that there's a fair bit of stuff left over too!
Enough epoxy to do 2 more planes (conservative - it depends on your skill with epoxy).
Enough Bullet Connectors to do another 2 Motor ESC combos.
Enough battery plugs to do another 4 ESC's.
some leftover carbon.
8 leftover control rods
8 left over clevises
Enough velcro and hinge tape for another 10 or so planes.
Enough leftover ply to cut half a bazillion motor mounts and control horns.
Bunches of leftover screws.
To do another plane I'd only have to buy a motor and ESC, a pair of servos, 1 carbon tube, and printouts (and a plan if you want to build a different plane).
Step 3: Build!
Missing Video: Electronics (esc/servo/Rx installation).
It's on it's way!!
At this stage the plane ended up with an "all up weight" (AUW) of 482 grams (with a Zippy 1600mAh 3s 20c Lipo battery and Orange RX) giving me a thrust to weight ratio of about 1.8:1.
The thrust-to-weight ratio was important to me to allow for people using different foams. Because I haven't included foam in the budget I wanted to allow for heavier foams (which are often cheaper) that people could choose to cut costs while still preserving a good power to weight ratio.
The thrust-to-weight ratio was important to me to allow for people using different foams. Because I haven't included foam in the budget I wanted to allow for heavier foams (which are often cheaper) that people could choose to cut costs while still preserving a good power to weight ratio.
Part 4: The Maiden Flight!
Ok, an important part here is that this plane is according to the designer's recommendations. It uses stuff virtually identical to the RCPowers master parts list and it's on the stock elevon setup with stock throws.
This is always a good idea. Maiden as close to stock as you possibly can with the boundaries of common sense. It's the easiest way to help ensure yourself a successful maiden flight and to get a peek into how the plane was expected to handle.
If you want different throws or a different CG etc, Mess with that stuff afterwards!
Part 5: But it's not finished!
I didn't do some of the work I usually do. There's no rounding or bevelling of any surface, one of the elevons is a little crooked on the mount. The hatch isn't even held down with Magnets (something I don't recommend unless you've made a nice clean build where that hatch fits snugly!). The reason, as I said above, was so I could stop at this point and make a video to go along with this stage of the plane.
If the mood strikes you? You can stop right now. Without going one step further you now have a plane that performs well and is going to be a bunch of fun to fly.
If you think there's a good chance you are going to crash? I actually recommend stopping right here! Why go to all the effort if you are going to be building a replacement in a couple week's time? Get used to the plane, get better at flying and make the slick and polished one when you aren't going to be making it ugly again with repairs or even just writing it off!
If you think there's a good chance you are going to crash? I actually recommend stopping right here! Why go to all the effort if you are going to be building a replacement in a couple week's time? Get used to the plane, get better at flying and make the slick and polished one when you aren't going to be making it ugly again with repairs or even just writing it off!
Part 6: I chose elevons.
The main reason I chose elevons is aerobatic performance. Elevon only vs 4x4 was chosen for weight and simplicity of build. The last reason was the weight of the servos. Adding Ailerons or Rudders is another 10-20 minutes on your build time per control surface and another $6.00 per servo to the overall cost of your plane (you have extra tape for your hinges, leftover control rods and leftover ply for more control horns).
To tell the truth though, I just like elevons on these mid-motor planes for the vectored thrust. If you are really worried about the lack of a roll rate what you can do is drive the ailerons from the elevon servo. This is a cheap option that doesn't require extra servos and will beef up your roll rate. I could have done this at the same price with only minimal extra weight BUT I really didn't feel the need to after the maiden flight.
Note: A lot of people actively recommend rudders and they have a good point. I don't "recommend" them but they can be a good idea even if you rarely use them. The power-to-weight ratio of this plane will take an extra pair of servos and still remain high.
Note: A lot of people actively recommend rudders and they have a good point. I don't "recommend" them but they can be a good idea even if you rarely use them. The power-to-weight ratio of this plane will take an extra pair of servos and still remain high.
Part 7: Adding slick and polish... and speed!
53.8 mph (86.5 km/h) is in the "nice" range instead of the "impressive" one.
Unfortunately I lost some data due to a corrupted file and the video I took to doppler the pre-bevelled speed was lost. I ran it before I lost it and the top speed was 48.2 MPH so I've gained 5.6 mph just by taking some time to smooth out the leading edges.
This, however, is a step up in the "complicated" stakes and I didn't get away with it scott free. An issue or two did rise out of it.
This, however, is a step up in the "complicated" stakes and I didn't get away with it scott free. An issue or two did rise out of it.
Note: This is a placeholder video made quickly to get this info in here sooner rather than later. It will be replaced as time allows ;).
Even something as simple as bevelling your leading edges can give you issues. The same can be said for just about anything else.
- The heavier you make your plane, the more fussy it will be about it''s Centre of Gravity.
- The more control surfaces you add the more fiddly it gets to make the plane fly "right".
- The more powerful your motor, the straighter it has to be before it starts to cause issues (for a couple reasons).
- The faster your plane is the harder it is to get the throws right for a good balance of not too much at speed and not too little for slow flying control.
On top of this, the more things you add into the build that harder it becomes to track down problems. If you've got some roll, is it torque? Is it one of the 4 control surfaces a little bit out? Is it your bevelling not quite even? And so on. With a simple plane with a light or medium motor? One of your control surfaces is a little bit out and a bit of trim will sort it out.
The more of these things you add, the more skill you need to get it right and the longer it's going to take you to get it all sorted into one fully functional plane that's a joy to fly. While all of these issues are things you want to learn to sort out in the long run, the more you try to deal with up front the longer it's going to take you not only to get your plane flying right but the longer it's going to take to learn it all.
Issues aside, the results of the bevelling when done are generally very positive and were worth the effort. The issue with rolling out of inverted would make me reconsider the KF2 in future builds though!
Part 8: Painting to save weight.
Coming eventually!
<missing video: Stenciling patterns>
<missing video: Stenciling patterns>
Part 9: Would I change anything?
<Missing Video: Mig 29 v2 Music Video - 3-5 mins>
For me? Certainly not. It's a plane that performs well, has a nice balance, enough speed to keep me happy and is plenty aerobatic enough.
For others? There's two issues with this plane. Whether you "fix" them or not comes down to whether you are willing or able to do the necessary throttle management.
The ESC gets too hot. This is an issue with more than one cheap chinese ESC's. This esc came out of another plane and it got hot then too so it's been operating "overly hot" for months and hasn't missed a beat. The problem is that it's most likely doing damage over time. A 40A ESC would be a nice idea (about another $3.00 - $6.00).
The same can be said for the battery. Right now it's fine but it does come back a little warmer than I'd like. It's winter so it's nice and cool but come summer the heat and humidity might see me puffing a couple of batteries. So I've headed out and flown this plane on everything I can get my hands on up to a 2200mAh 3s 30C battery. It gets a little less aerobatic the heavier the battery gets but it still goes vertical for as long as you want it to. My preference was a Zippy 1800mAh 3s 20C. It came back nice and cool and shouldn't give me any problems in summer.
Also, you have to take into account that not everyone wants the same thing from a Parkjet. Some people want to press for speed, more control surfaces, a slick paint job and the like. Some even prefer a little added weight.
My honest thoughts on the matter? You just have to fly before you make your mind up on this stuff. It's that simple. I freely admit that speed doesn't interest me all that much but I still have two speed planes. One scratchbuilt and one storebought. I don't fly them as often as the rest but I still fly them when the mood takes me.
You are the one who is going to understand what you like and this setup is very "middle of the road". It's aerobatic but it's not as floaty as it could be. It's quick for the setup that's on it but a lot of other people's are faster. This plane will allow you to "feel out" the hobby after you have learnt to keep your planes in the air and are ready to move a little further along.
This setup is an ok basis to work from. It will take a sensible number of additions without giving it a poor thrust to weight ratio. You could safely add a pair of servos, move up a battery size and a heavier paint job and still have it push itself into unlimited vertical.
Part 10: Upgrading to "RTF... sort of".
All that's missing is a battery, a charger and a TX/RX combo and you are in RTF land except for having to build your plane yourself. You'll have everything you need to fly if you grab a couple more things.
Truth be told, you can get a charger and TX/RX combo on the cheap and have everything that you need to fly for about $100 which beats a lot of RTF planes. I honestly don't think it's the best option unless you have to do it to get into the air.
The Tx/Rx combo is something I don't like to go "complete budget" on. While about $24 will get you into the air and will work quite well, I honestly don't trust them to last. Light construction means a couple of hard knocks and things could go quite wrong. From a budget perspective, the Turnigy 9x has everything you'll need for flying your scratchbuilt Parkjets with a more solid constriction giving added reliability.
Turnigy 9x + 8ch Reciever combo.
Chargers are also something you can go cheap on and I'm less fussy in this department. However I do recommend a decent computerized charger. Surprizingly you can get out of this quite cheap, under $20.
Hobbyking Eco 6.
You will also need a 12v power supply if you want to use these indoors. You can pick these up in department stores for $5-$10 on a regular basis.
After that, it's your choice of battery.
This bumps the price. Up to $149.37. Add in the cost of foam (and lets go the expensive stuff) and we're up to $171.87. An decent RTF will run you $120-$140 which is cheaper of course. The difference?
You have a bunch of spare parts making your next couple of planes a cheaper outlay, you have a decent charger, a 9ch TX you can grow with and you built it yourself!
It's all about spending the money you have intelligently. Sure, you can buy a large, scale-looking RTF with retracts and probably a couple extra bells and whistles for that kind of money. However, you just arent' going to be in nearly as good of a position to enter the hobby as these suggestions will.
Part 11: Where to go from here.
As mentioned, you've now got a bunch of spare parts that's going to make the next 3 planes cheaper.
The benefit in scratchbuilt parkjets comes more in the long run. Your next plane will be cheaper and you now have a 9 ch TX with multiple model memory. Not only can you run your scratchbuilt parkjets off one, it's reliable enough for storebought parkflyers too.
You also have a charger suitable for charging a range of batteries at the appropriate rate also opening up PnF storeboughts.
Everything now becomes cheaper because you made smart purchases up front. As long as you are going to stay in the hobby? A computerized Transmitter and a decent charger are a very smart buy that will save you hundreds of dollars.
If you want more speed?
<missing video - short doppler vid RCP T-50 v1 with same motor/ESC/Prop/Batt combo for speed comparison>
Simply choosing a plane more suited to speed on this setup will achieve good results without having to move up to more expensive motor/ESC combos.
Part 12: Project Summary.
<Missing video - Project summary - how I feel about the plane overall, the goals achieved or missed, and a short word on the next project and how it follows on from this one!>
<unfinished>
The same can be said for the battery. Right now it's fine but it does come back a little warmer than I'd like. It's winter so it's nice and cool but come summer the heat and humidity might see me puffing a couple of batteries. So I've headed out and flown this plane on everything I can get my hands on up to a 2200mAh 3s 30C battery. It gets a little less aerobatic the heavier the battery gets but it still goes vertical for as long as you want it to. My preference was a Zippy 1800mAh 3s 20C. It came back nice and cool and shouldn't give me any problems in summer.
<missing video - flight comparison - Zippy Lipoly 1600mAh 3s 20c (123g) Vs Turnigy 2200mAh 3s 30-40C (190g)>
Also, you have to take into account that not everyone wants the same thing from a Parkjet. Some people want to press for speed, more control surfaces, a slick paint job and the like. Some even prefer a little added weight.
My honest thoughts on the matter? You just have to fly before you make your mind up on this stuff. It's that simple. I freely admit that speed doesn't interest me all that much but I still have two speed planes. One scratchbuilt and one storebought. I don't fly them as often as the rest but I still fly them when the mood takes me.
You are the one who is going to understand what you like and this setup is very "middle of the road". It's aerobatic but it's not as floaty as it could be. It's quick for the setup that's on it but a lot of other people's are faster. This plane will allow you to "feel out" the hobby after you have learnt to keep your planes in the air and are ready to move a little further along.
This setup is an ok basis to work from. It will take a sensible number of additions without giving it a poor thrust to weight ratio. You could safely add a pair of servos, move up a battery size and a heavier paint job and still have it push itself into unlimited vertical.
Part 10: Upgrading to "RTF... sort of".
All that's missing is a battery, a charger and a TX/RX combo and you are in RTF land except for having to build your plane yourself. You'll have everything you need to fly if you grab a couple more things.
Truth be told, you can get a charger and TX/RX combo on the cheap and have everything that you need to fly for about $100 which beats a lot of RTF planes. I honestly don't think it's the best option unless you have to do it to get into the air.
The Tx/Rx combo is something I don't like to go "complete budget" on. While about $24 will get you into the air and will work quite well, I honestly don't trust them to last. Light construction means a couple of hard knocks and things could go quite wrong. From a budget perspective, the Turnigy 9x has everything you'll need for flying your scratchbuilt Parkjets with a more solid constriction giving added reliability.
Turnigy 9x + 8ch Reciever combo.
Chargers are also something you can go cheap on and I'm less fussy in this department. However I do recommend a decent computerized charger. Surprizingly you can get out of this quite cheap, under $20.
Hobbyking Eco 6.
You will also need a 12v power supply if you want to use these indoors. You can pick these up in department stores for $5-$10 on a regular basis.
After that, it's your choice of battery.
This bumps the price. Up to $149.37. Add in the cost of foam (and lets go the expensive stuff) and we're up to $171.87. An decent RTF will run you $120-$140 which is cheaper of course. The difference?
You have a bunch of spare parts making your next couple of planes a cheaper outlay, you have a decent charger, a 9ch TX you can grow with and you built it yourself!
It's all about spending the money you have intelligently. Sure, you can buy a large, scale-looking RTF with retracts and probably a couple extra bells and whistles for that kind of money. However, you just arent' going to be in nearly as good of a position to enter the hobby as these suggestions will.
Part 11: Where to go from here.
As mentioned, you've now got a bunch of spare parts that's going to make the next 3 planes cheaper.
The benefit in scratchbuilt parkjets comes more in the long run. Your next plane will be cheaper and you now have a 9 ch TX with multiple model memory. Not only can you run your scratchbuilt parkjets off one, it's reliable enough for storebought parkflyers too.
You also have a charger suitable for charging a range of batteries at the appropriate rate also opening up PnF storeboughts.
Everything now becomes cheaper because you made smart purchases up front. As long as you are going to stay in the hobby? A computerized Transmitter and a decent charger are a very smart buy that will save you hundreds of dollars.
If you want more speed?
<missing video - short doppler vid RCP T-50 v1 with same motor/ESC/Prop/Batt combo for speed comparison>
Simply choosing a plane more suited to speed on this setup will achieve good results without having to move up to more expensive motor/ESC combos.
Part 12: Project Summary.
<Missing video - Project summary - how I feel about the plane overall, the goals achieved or missed, and a short word on the next project and how it follows on from this one!>
<unfinished>
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